Comparative analysis of long-term results of high-tech external beam therapy and combined radiotherapy in patients with prostate cancer and high risk of progression

Background. Patients suffering from prostate cancer (PCa) with a high risk of progression need the most active treatment tactics. Escalation of radiation dose, larger daily fractions radiation therapy (including high-dose-rate interstitial brachytherapy (HDR-BT)) is a promising approach to the treatment of PCa. Objective of the study. Comparative assessment of the long-term treatment results of patients with PCa with a poor prognosis after external beam radiotherapy (EBRT) and combined radiation therapy, depending on risk factors. Materials and methods. 207 patients who received a course EBRT and HDR-BT with EBRT (combined RT) on a radical program for the first detected PCa at the N.N. Alexandrov National Cancer Center of Belarus in 2013-2015 inclusive. All patients were belonged to the group of high and very high risk of progression according to the criteria of the NCCN (National Comprehensive Cancer Network), all were treated with neoadjuvated hormone therapy (medical or surgical castration). The patients were stratified into two groups: HDR-BT with EBRT and EBRT. When conducting combined RT, HDR-brachytherapy was performed in single fraction with a dose of 11.5 Gy, for EBRT it was used as a conventional fractionation (single dose of 2 Gy, total - 44 Gy) and hypofractionation (single dose of 3 Gy, total - 36 Gy). Patient that were not who not included in the combined RT protocol were treated with EBRT under a radical program in a total dose of 78-80 Gy. Results. It was established that in the group of patients after EBRT the median survival was not achieved, the 5-year adjusted survival (AS) was 85.2 +/- 5.6 %. In the combined RT group, the median survival was also not reached, the 5-year-old AS was 92.2 +/- 5.9 %. It was found that for the patients with a Gleason score of 7 or more, a significant difference in the AS index was obtained in favor of the HDR-BT with EBRT: the 5-year AS of patients of this subgroup who were exposed to combined RT was 84.6 +/- 9.8 %, while after EBRT, the 5-year-old AS was 71.0 +/- 11.2 %. In the subgroup of patients with Gleason sum 7-10, combined RT was associated with statistically significantly better long-term results in compared with EBRT. Conclusion. The application of the method of combined RT for patients suffering from PCa with a high risk is characterized with satisfactory long-term treatment results.